Allocation Rules and Meter Timing Issues in Local Energy or 'Peer to Peer' Networks

Abstract

The growing adoption of distributed energy resources (DERs) across Australia may represent the start of a transition of Australia's power system from a centralised generation model towards an interconnected set of embedded microgrid systems. In these systems, local trading of coincident generation and consumption is being explored, with the idea that this would encourage consumer engagement, provide more choice, and incentivise reduced use of networks (via increased balancing of loads and generation locally). However coincidence of generation and load over short time frames, and hence network benefit, can be difficult to determine using existing metering systems. There are many sites undergoing trials to determine how energy flows can be efficiently monitored and accounted for in microgrid systems. At the current time, commercial metering is generally performed on time scales greater than thirty seconds, with most metering systems measuring net flows on half-hourly intervals. This represents a barrier to accurate accounting, since the time at which nodes generate and consume energy within a wide metering period is not known. As a result, end-users may face effective penalties or avoid charges that would accrue to their generation or consumption profile under more accurate accounting. Accurate accounting for the economic benefits of embedded microgrids that result from either reductions in external network use or contributions to improved reliability, rely on sub-second level timing, and cannot be commercially factored (or incentivized) without corresponding metering. In this paper, the coincidence of generation and consumption in a micro-grid setting is examined over different timeframes using a software based simulation, and the impact of different time intervals for accounting is explored using an algorithmic theoretical approach. It is found that there are predictable trends in the way that metering time periods impact the accuracy of 'peer to peer' accounting. For the limited dataset tested, the inaccuracies were found to be small relative to overall energy consumption, however further work is required to determine whether this can be generalized across the majority of schemes.